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Dear Colleagues,

In Asia, many researchers are devoted to the dissemination of new and original knowledge in all branches of analytical chemistry. In order to assemble these findings, a Special Issue entitled “Analytical Chemistry in Asia” is being launched. This Special Issue will present a high-quality collection comprising work from scientists in Asian countries. Both original research articles and comprehensive review papers are welcome.

This Special Issue will discuss new knowledge or cutting-edge developments in the field of Analytical chemistry, with the aim of expanding the current body of knowledge. This Issue is intended as a forum for the exchange of research findings and innovative ideas in the field.

Dr. Makoto Tsunoda
Guest Editor

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Keywords

analytical chemistry
Asia
HPLC
sample preparation
bioanalysis
mass spectrometry

Published Papers (2 papers)

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Research

10 pages, 951 KiB

Open AccessArticle

Development of a Two-Dimensional Liquid Chromatographic Method for Analysis of Urea Cycle Amino Acids

by Yuko Sumida and Makoto Tsunoda

Molecules 2024, 29(3), 700; https://doi.org/10.3390/molecules29030700 - 2 Feb 2024

Viewed by 838

Abstract

The urea cycle has been found to be closely associated with certain types of cancers and other diseases such as cardiovascular disease and chronic kidney disease. An analytical method for the precise quantification of urea cycle amino acids (arginine, ornithine, citrulline, and argininosuccinate) by off-line two-dimensional liquid chromatography (2D-LC) combined with fluorescence-based detection was developed. Before analysis, the amino acids were derivatised with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) to obtain NBD-amino acids. The first dimension involved the reversed-phase separation, in which NBD derivatives of urea cycle amino acids were completely separated from each other and mostly separated from the 18 NBD-proteinogenic amino acids. The samples were eluted with stepwise gradient using 0.02% trifluoroacetic acid in water–acetonitrile as the mobile phase. In the second dimension, an amino column was used for the separation of NBD-ornithine, -citrulline, and -argininosuccinate, while a sulfonic acid column was used to separate NBD-arginine. The developed 2D-LC system was used to analyse human plasma samples. The fractions of NBD-urea cycle amino acids obtained in the first dimension were collected manually and introduced into the second dimension. By choosing appropriate mobile phases for the second dimension, each NBD-urea cycle amino acid eluted in the first dimension was well separated from the other proteinogenic amino acids and interference from endogenous substance. This could not be achieved in the first dimension. The urea cycle amino acids in human plasma sample were quantified, and the method was well validated. The calibration curves for each NBD-urea cycle amino acid showed good linearity from 3 (ASA) or 15 (Orn, Cit, and Arg) to 600 nM, with correlation coefficients higher than 0.9969. The intraday and interday precisions were less than 7.9% and 15%, respectively. The 2D-LC system is expected to be useful for understanding the involvement of the urea cycle in disease progression. Full article

(This article belongs to the Special Issue Analytical Chemistry in Asia)

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13 pages, 3365 KiB

Open AccessArticle

The Development of an Extraction Method for Simultaneously Analyzing Fatty Acids in Macroalgae Using SPE with Derivatization for LC–MS/MS

by Taewoo Yum, Eun-Yong Kim, Yeongeun Kim, Sukyoung Choi and Ki-Jung Paeng

Molecules 2024, 29(2), 430; https://doi.org/10.3390/molecules29020430 - 16 Jan 2024

Viewed by 824

Abstract

Fatty acid analysis is an essential step in evaluating the potential of macroalgae for biodiesel production. An extraction method was developed to simultaneously analyze up to five types of biodiesel-fuel-related fatty acids (myristic acid, palmitic acid, cis-palmitvaccenic acid, stearic acid, and oleic acid) in macroalgae using liquid chromatography and tandem mass spectrometry (LC–MS/MS). Lypophilization and solid-phase extraction (SPE) techniques were applied to improve the extraction efficiency and effectively purify samples. The optimal conditions for SPE were set by comparing the recoveries according to the various solvent conditions for each step (loading, washing, and elution). In addition, the introduction of trimethylaminoethyl (TMAE) derivatives to the hydroxyl group of the target analyte increased the ionization efficiency and sensitivity. The derivatized samples were analyzed using the LC–MS/MS method with electrospray ionization in the positive and multiple-reaction monitoring modes. The target analytes were separated and detected within 13.5 min using a CAPCELL PAK C18 MGII S3 column. Gradient elution was performed using distilled water and acetonitrile containing 5 mM ammonium acetate. This method offers a reliable and sensitive tool for the analysis of macroalgae samples for their potential use in biodiesel production. To the best of our knowledge, this is the first report on the simultaneous determination of fatty acids in macroalgae using LC–MS/MS with TMAE derivatization. Full article

(This article belongs to the Special Issue Analytical Chemistry in Asia)

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